Velocity Keyboard
Velocity Keyboard is a velocity sensitive onscreen keyboard from Blue Mangoo the creators of iFretless Bass and other iOS instruments.
App type: AUv3
App store link: 
Developer's Audiobus forum handle is: @Blue_Mangoo
Videos
The following videos demonstrate this app.
Setting up Aftertouch MIDI CC Controls
Video Review by Rick Middleton
SoundTest Room Live Stream
@flo26 improv (BeatHawk classical guitar played with Velocity Keyboard)
Tips and Tricks
Setting Up Velocity Sensitivity in Target Apps/AUs
While Velocity Keyboard sends velocity information and CCs, the synths or samplers you are controlling need to be set up to respond to this information. Many synth patches are not set up to be velocity-sensitive. Below are videos that were created to walk people through the steps required to set up patches to be velocity sensitive:
Setting up Factory
Setting up Roli Noise
Setting up Thor
Setting up Animoog
Cubasis
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